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Re: The type/object distinction and possible synthesis of OOP and imperative programming languages

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On 4/16/2013 1:29 PM, Ethan Furman wrote:
> On 04/16/2013 01:25 AM, Serhiy Storchaka wrote:
>> On 16.04.13 07:46, Ian Kelly wrote:
>>> On Mon, Apr 15, 2013 at 9:17 PM, Terry Jan Reedy <tjreedy@udel.edu>
>>> wrote:
>>>> I will keep the above in mind if I write or review a patch. here are 4
>>>> non-subclassable builtin classes. Two are already documented. Bool
>>>> in one,
>>>> forget which other. I believe it was recently decided to leave the
>>>> other two
>>>> as is given the absence of any practical use case.
>>>
>>> The four are bool, NoneType, slice and ellipsis, I believe.
>>
>> --> import builtins
>> --> for n in dir(builtins):
>> ...     if type(getattr(builtins, n)) is type:
>> ...         try:
>> ...             t = type(n, (getattr(builtins, n),), {})
>> ...         except TypeError as e:
>> ...             print(e)
>> ...
>> type 'bool' is not an acceptable base type
>> type 'memoryview' is not an acceptable base type
>> type 'range' is not an acceptable base type
>> type 'slice' is not an acceptable base type
>
> Well that bumps our count to five then:
>
> --> NoneType = type(None)
> --> NoneType
> <class 'NoneType'>
> --> class MoreNone(NoneType):
> ...   pass
> ...
> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
> TypeError: type 'NoneType' is not an acceptable base type

'NoneType' is not a builtin name in builtins, which is precisely why you 
accessed it the way you did ;-). From issue 17279 (for 3.3):

"Attached subclassable.py produces these lists:
Among named builtin classes, these cannot be subclassed:
bool, memoryview, range, slice,
Among types classes, these can be subclassed:
ModuleType, SimpleNamespace,"

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The type/object distinction and possible synthesis of OOP and imperative programming languages Mark Janssen <dreamingforward@gmail.com> - 2013-04-14 20:48 -0700
  Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-04-15 10:11 +0000
    Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-04-15 19:43 +0200
      Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-04-16 02:15 +0000
    Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Dave Angel <davea@davea.name> - 2013-04-15 17:13 -0400
      Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Rotwang <sg552@hotmail.co.uk> - 2013-04-15 23:12 +0100
        Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Chris Angelico <rosuav@gmail.com> - 2013-04-16 08:32 +1000
          Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Rotwang <sg552@hotmail.co.uk> - 2013-04-15 23:54 +0100
        Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Mark Janssen <dreamingforward@gmail.com> - 2013-04-16 15:38 -0700
          Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-04-17 06:40 +0000
            Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Chris Angelico <rosuav@gmail.com> - 2013-04-17 16:56 +1000
            Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Chris Rebert <clp2@rebertia.com> - 2013-04-17 00:16 -0700
            Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-04-17 18:40 -0400
        Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Ian Kelly <ian.g.kelly@gmail.com> - 2013-04-16 17:14 -0600
        Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Michael Torrie <torriem@gmail.com> - 2013-04-18 10:37 -0600
          Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Neil Cerutti <neilc@norwich.edu> - 2013-04-18 17:57 +0000
          Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-04-19 01:00 +0000
            Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Roy Smith <roy@panix.com> - 2013-04-18 21:08 -0400
              Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Mark Janssen <dreamingforward@gmail.com> - 2013-04-18 18:24 -0700
              Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Ned Batchelder <ned@nedbatchelder.com> - 2013-04-18 22:10 -0400
              Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Mark Janssen <dreamingforward@gmail.com> - 2013-04-18 19:30 -0700
                Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-04-19 03:38 +0000
              Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Ned Batchelder <ned@nedbatchelder.com> - 2013-04-18 22:39 -0400
              Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Mark Janssen <dreamingforward@gmail.com> - 2013-05-01 13:32 -0700
                Re: The type/object distinction and possible synthesis of OOP and imperative programming languages alex23 <wuwei23@gmail.com> - 2013-05-01 18:13 -0700
    Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Terry Jan Reedy <tjreedy@udel.edu> - 2013-04-15 20:52 -0400
      Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-04-16 02:32 +0000
        Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Terry Jan Reedy <tjreedy@udel.edu> - 2013-04-15 23:17 -0400
        Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Ian Kelly <ian.g.kelly@gmail.com> - 2013-04-15 22:46 -0600
        Re: The type/object distinction and possible synthesis of OOP and imperative programming languages rusi <rustompmody@gmail.com> - 2013-04-15 21:56 -0700
          Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-04-16 05:59 +0000
        Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Serhiy Storchaka <storchaka@gmail.com> - 2013-04-16 11:25 +0300
        Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-04-16 11:07 +0200
        Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Terry Jan Reedy <tjreedy@udel.edu> - 2013-04-16 12:49 -0400
        Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Ethan Furman <ethan@stoneleaf.us> - 2013-04-16 10:29 -0700
        Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Terry Jan Reedy <tjreedy@udel.edu> - 2013-04-16 14:29 -0400
        Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Ian Kelly <ian.g.kelly@gmail.com> - 2013-04-16 12:22 -0600
        Re: The type/object distinction and possible synthesis of OOP and imperative programming languages Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-04-17 14:04 +0200
  Re: The type/object distinction and possible synthesis of OOP and imperative programming languages 88888 Dihedral <dihedral88888@googlemail.com> - 2013-04-15 23:54 -0700
  Re: The type/object distinction and possible synthesis of OOP and imperative programming languages 88888 Dihedral <dihedral88888@googlemail.com> - 2013-04-15 23:54 -0700
  Re: The type/object distinction and possible synthesis of OOP and imperative programming languages rusi <rustompmody@gmail.com> - 2013-04-21 08:44 -0700

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